If you're ever in a situation where you have canned food but no way to open it you can grind the can lid against a concrete form such as a parking stop to wear down the top of the can so that the lid is opened without spilling the food.

This tip comes from YouTube user who read about it in survival expert Cody Lundin's book When All Hell Breaks Loose. Basically, most modern food cans have lids that are a rolled seam; if you can grind through that seam you can get at the food inside without spilling anything other than perhaps a bit of liquid.

Place the can you want to open upside down on your concrete surface and grind it back and forth using your best "wax-on wax-off" motion. After a minute or so you should see a bit of moisture on the concrete—that is the sign you've broken through the seal. Pick the can up and use any metal tool to finish prying the lid off. This shouldn't take much effort since you've already broken through most of the can's seal.